| The geographical advantages of Guangxi's coastal areas are significant.They have excellent deep-water terminals and are an extremely important part of the Beibu Gulf Economic Zone.It is responsible for the historical mission of facing the ASEAN and connecting the southwest to the sea.The area within the study area is rich in species and has high vegetation coverage.Its ecological environment is highly concerned by the academic community and the government.In 2008,the State approved the implementation of the “Guangxi Beibu Gulf Economic Zone Development Plan”,and the development of the Guangxi coastal area has taken a new step.With the overall development of society and economy and the continuous expansion of urban and rural areas,the degeneration of habitat function,the continuous decline of carbon storage,the decline of habitat quality,and the scarcity of habitats have occurred.With the continuous reduction in the area of forest land in the study area,the rapid increase in the scale of aquaculture water area,the continuous and rapid expansion of urban and rural land use scale and the scale of industrial and mining land,the ecological environment of coastal areas of Guangxi is facing tremendous pressure,and the research area is responsible for the dual tasks of emphasizing the development and protecting environment.In this paper,3 phases remote sensing images of the Guangxi coastal areas in 2005,2010,and 2015 were selected,and the land use classification map of the 3 phases of the study area was obtained through remote sensing interpretation.Combining with the Guangxi Statistical Yearbook and land use change,the characteristics of changes in the time scale and their causes were analyzed.The land use transfer matrix system was used to analyze the transitions between different types of coastal areas in Guangxi and combined them.The policy situation and geographic location of the study area analyzed the reasons for the change.The In VEST Model Biodiversity Module was used to evaluate the quality of habitat in Guangxi's coastal areas from 2005 to 2015,and the reasons for the changes in habitat quality in the study area from 2005 to 2015 were analyzed.In addition,the carbon storage and fixed module analysis using the In VEST model was used in this paper.The characteristics of changes in carbon stocks in the study area from 2005 to 2015 and the reasons for changes in carbon stocks.The main conclusions of this paper are as follows:(1)The coastal areas in Guangxi are mainly planted forest lands,followed by dry and paddy fields.According to the analysis of land use area change,the change of construction land and unused land in 2005-2010 is more obvious,and the changes in other areas are relatively small.The main reason is that the scale of construction land has been significantly expanded during this time period.Suburban land has become a large number of urban areas and urban population has increased rapidly.This has further accelerated the supply of residential land and commercial land,and the scale of construction land has been further expanded.The change in land use structure from 2010 to 2015 was extremely significant.In 2015,the grassland area accounted for 4.62% of the total area,a decrease of 12.16 percentage points compared with 2010,and the decrease was more obvious.The main reason is that grassland is mainly transferred to forest land,followed by construction land,dry land and water area.The largest reduction is in paddy fields.In 2015,the planting area of paddy fields accounted for 12.27% of the total area,a decrease of 6.34% compared with 2010.The expansion of the scale of construction land is very significant.The rapid advancement of industrial and mining traffic,the continuous expansion of towns,and the rapid development of tourism have all greatly increased the scale of construction land.(2)Through land use change transfer matrix analysis,it was concluded that the land-based shifts in paddy fields,dry lands,and grasslands during 2005-2010 were mainly converted to construction land,but the amount of shifts in the changes was not significant.In the period from 2010 to 2015,the shifts among various types of species have changed significantly.From 2010 to 2015,the major shifts in paddy fields have changed into construction land;the dry land has been largely transferred to forest lands for planting economic forests,followed by construction land and paddy fields;forest lands have been mainly transferred to dry lands.Secondly,construction land and grassland are used;grassland is mainly transferred to forest land for planting economic forests;water areas are mainly transferred to construction lands;and construction land reclamation is mainly transferred to grassland and dry land.(3)Combined with the comprehensive evaluation results of land-use change characteristics and habitat quality,the overall habitat situation in the study area from 2005 to 2015 was good,and the area of non-degradation area accounted for nearly half.However,considering the changes in time series,the habitat situation in the study area showed a downward trend from 2005 to 2015;the overall habitat quality in the study area was better,and nearly half of the regional habitat scores were medium to high.The highest value of habitat quality scores is in the Fangcheng District,mainly because there are 100,000 mountains in the Fangcheng District,and the vegetation coverage is extremely high,reaching over 90%,and the habitat quality is excellent.Followed by Dongcheng City,Fangchenggang,the quality of habitat in Qinnan District was middle;the quality of habitat in Beihai City had the lowest score;the results of habitat scarcity analysis showed that the ecological environment in most areas of the study area had good integrity,and the overall habitat in the study area was generally stable,accounting for the study area.The proportion of the total area is 67.55%.The scarcity of habitat types and the frequent internal and regional instability of the intraplates are mainly distributed in Tieshangang District,Yinhai District,Haicheng District,Hepu County and Qinnan District.(4)Combining the characteristics of land-use change and comprehensive evaluation of carbon storage and fixation,the carbon reserves in the study area in 2005,2010,and 2015 ranged from 19.67 t/hm2 to 31.37 t/hm2,and carbon storage city 2005-2015.The overall decline trend,and the decline in carbon stocks from 2010 to 2015 is far greater than the decline in carbon stocks from 2005 to 2010.This is mainly due to the fact that the research area in 2010-2015 was in a golden period of development.The scale of land for urban and rural construction has been greatly increased,the scale of land for industrial and mining traffic has continued to expand,and the area of aquaculture waters has increased significantly. |
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